Generally, beamforming in a wireless communication system focuses on forming directional transmission or reception signal power in the direction of an intended respective receiver or transmitter. Transmission and reception of wireless signals can benefit from beamforming in that beamforming lessens the power needed to perform the transmission of wireless signals and lessens the power causing interference directed to non-intended receivers. From a receiver's perspective, beamforming enhances the desired received signal and lessens the interference due to other transmitters or signal sources. The stronger a formed beam capacity, the higher the signal quality in the intended wireless receiver or transmitter.
Various beamforming schemes have been selected to reach a desired beamforming capacity. For example, dirty paper coding was contemplated to achieve a maximum capacity for the broadcasting channel. This approach, however, is complex and requires full channel status information which is prohibitive to be implemented in current state of the art systems. For practical solution, closed-loop (multiple-input multiple-output) MIMO techniques with precoding matrix index feedback have been proposed and selected in current wireless communications standards. However, for such techniques the amount of feedback required is proportional to the number of streams; in case of multiple users within a cell, this amount is considerable. Opportunistic beamforming schemes have also been proposed to reduce the feedback amount. While the asymptotic performance of opportunistic beamforming approaches close to that with full channel state information (CSI) feedback as the number of users increases, the performance under relatively small number of users degrades significantly.
What is needed, then, is an improved method of beamforming and systems employing same that overcome the shortcomings of the prior art.